An explosives and drugs detector based on ion mobility spectrometry is a quick, sensitive and portable on-site detection instrument which has been applied for military purposes or used by security inspection organizations to detect chemical warfare agents, explosives, drugs, etc.
When an ion mobility spectrometer detects contraband compounds, in addition to a vapor sampling mode (generally called “odor smelling” mode), particle sampling is the most commonly used sampling mode. By adopting the particle sample collection mode, a sampling wipe is first used to wipe the surface of an object to collect particulates of explosives or drugs, and then the wipe is inserted into the sample inlet port of the instrument for detection and identification.
Currently particle sampling for an ion mobility spectrometer is conducted in two modes:
1. Direct Wiping
In this mode, an operator manually holds the sampling wipe to directly wipe the surface of an object. To avoid the hand from contacting the surface of the object (the contaminated hand may interfere with the subsequent sampling and detection), the sampling wipe has to be made very large and correspondingly the sample inlet port of the instrument is also made very large. This will not only cause great waste of sampling wipes, and, more importantly, such a very large sample inlet port has a lot of drawbacks: firstly, uncentralized heat and the resultant low heating efficiency adversely affect the sensitivity of the instrument; secondly, a large electrical power consumption shortens the working time of the battery so that the battery needs to be replaced frequently, thus affecting the application performance of the instrument.
2. Wiping Using a Sampling Device
At present, there is a kind of apparatus which can hold a sampling wipe for sample swiping. A paper holder like a paper clip is provided at the front end of the apparatus and opens forwardly. After the front end of the sampling wipe is fixed, it must be folded backwardly 180 degrees to be fixed on the wiping means. Therefore the front end of the sampling wipe forms an obvious fold. The sampling wipe must be restored to a flat and straight state after the sampling wipe is folded so that the sampling wipe can be easily inserted into the sample inlet port. Common plant fiber paper can hardly be restored to the flat and straight state after being folded. For this reason, the wiping means uses specially prepared sampling “paper” (chemical polymer) which is costly to use and exhibits a low sampling efficiency which may affect the detection performance of the instrument. In addition, the wiping contact surface of the wiping means is a flat surface so that when being used to wipe the surface of the object with a certain curvature, the sampling wipe cannot sufficiently contact the surface of the object, thus affecting the wiping and sampling efficiency.